US Senate(NEW YORK) -- Sen. Robert Menendez, D-N.J., had an unpaid intern working in his district office who is a registered sex offender and an illegal immigrant. The intern is now facing deportation, a Department of Homeland Security official confirms.

A U.S. official confirms to ABC News that an arrest was made of the intern, 18-year-old Luis Abrahan Sanchez Zavaleta from Peru, on December 6.

The office of Sen. Menendez was informed Monday of the arrest and the senator was informed on Wednesday, the senator confirmed. The senator defended his office’s action Wednesday, emphasizing that the intern applied, was recommended and vetted by his school for the internship, not the senator’s office.

“We asked status of all of those college interns, nothing didn’t indicate anything about his status and we certainly wouldn’t have known through any background checks since he is a minor about any sex offender status,” Menendez said during an appearance on MSNBC Wednesday afternoon.

Once Menendez’s office was informed of the arrest, the senator’s New Jersey staff director let the intern go from the program.

“He’s an unpaid college intern so it’s not like he’s a staff paid person,” Menendez said. “There is no way we could know about his status. We ask about status…there is no way we could know about any allegation as a juvenile about what his background would be in terms of any criminality.”

Menendez is an advocate for immigration reform and noted during his MSNBC appearance Wednesday that this underscores the urgency of such reform.